Joints, synovial fluid and cartilage Flashcards
what are the different types of joint ?
fibrous - periodontal, sutures, interosseous
cartilaginous - primary (hyaline), secondary (hyaline + fibrocartilage)
synovial - plane, hinge, pivot, ellipsoid, saddle, ball and socket
what contributes to joint stability ?
shape of articulations surfaces
capsule and ligaments
muscles
what are features of articular (hyaline) cartilage ?
superficial layer - flattened chondrocytes that produce collagen + glycoproteins
transitional layer - round chondrocytes that produce proteoglycans
>75% water
what are glycoproteins ?
proteins with oligosaccharide chains attached, protein>carb
lubricant
what are proteoglycans ?
heavily glycosylated proteins, carb>protein
aggrecan
what are glycosaminoglycans GAGs ?
long unbranched polysaccharides, highly polar attract water
hyaluronic acid
why is synovial fluid important ?
transports nutrients and removes waste form cartilage as it is avascular and alymphatic
how is synovial fluid produces ?
synoviocytes in the synovium produce it
rich capillary network with no epithelial lining
direct exchange of O2, CO2 and metabolites between blood and synovial fluid
what are the different types of synoviocytes ?
type A - like macrophages, remove debris, contribute to fluid production
type B - fibroblast like, main producer of synovial fluid
what are key features of synovial fluid ?
viscous hyaluronic acid and lubricin fluid component from plasma small volumes 0.5 in knee rapid turnover - 2 hours
what is the function of synovial fluid ?
nutrition
removal of waste
lubrication
what changes are seen in ageing joints ?
increased synovial fluid viscosity - slower movements, reduced lubrication
decreased water content of cartilage - reduced shock absorption
less protection = increased risk of damage
